1. Field of the Invention
This invention relates to an apparatus for reproducing a video signal which is recorded in one of a plurality of recording modes on a recording medium such as a magnetic tape, which can discriminate the recording mode automatically so as to change over the reproducing speed accordingly. More specifically, this invention relates to automatic discrimination of the recording mode in an apparatus of the so-called pilot signal system, in which a magnetic tape is used as a magnetic recording medium, and pilot signals for tracking control are recorded in the magnetic tape in superposition on the video signal, in place of tracks in which a tracking control signal is recorded.
2. Description of the Prior Art
A method of tracking control by the pilot signal system is proposed in the U.S. Pat. No. 4,297,733.
As a magnetic recording and reproducing apparatus employing the pilot signal system for tracking control, recently a small-sized magnetic recording and reproducing apparatus called "8 mm VIDEO" is attracting a keen attention. This small-sized magnetic recording and reproducing apparatus includes a standard recording mode and a standard reproducing mode at a standardized playing tape speed, and a long playing recording mode and a long playing reproducing mode at a half of the standard playing tape speed for long-term recording and reproducing. Accordingly, in reproducing, it is necessary to discriminate at which recording mode the video signal has been recorded.
In a VHS type magnetic recording and reproducing apparatus or a Beta type magnetic recording and reproducing apparatus presently available on market, the recording mode is discriminated by a reproduced control signal for tracking control which is detected from the control track in the magnetic tape, and the reproducing speed is automatically changed over.
However, in the 8 mm VIDEO employing the pilot signal system for tracking control, a magnetic tape does not have control track. Therefore, in order to discriminate the recording mode automatically, it is necessary to provide a new circuit not relying on a reproduced control signal.
An example of system for determining a recording speed of a magnetic tape which a video tape recorder of the pilot signal system is in a reproducing mode, which has close relation with the present invention, is shown in Japanese Patent Laying-Open Gazette No. 19260/1984. However, the determining system disclosed in this gazette involves disadvantages that when an erroneous frequency is detected, even if instantaneously, due to noises and the like, the determining circuit is switched on, causing errors in the detection of the recording mode.